Scale the model, with automatically scaling UV's
The UV's are independent from the scale of the object so if you scale the object, the texture on it is scaled with it. 

If you wanted to have functionality where you scale the object, but the texture remains the same size in relation to it's surroundings, you could use a driver to drive a multiplier for UV coordinates in the shader's nodes to adjust the size of the texture to remain the same size, however if you wish to move vertices around in 3d and UVs to be updated somehow, that functionality does not exist, because you move vertices in 3d space and UVs are in 2d and there is no one right way to define how to translate those transforms from 3d space to 2d space. There could be many ways to do this and it is hard to define the one that would be desired in a UV map. One could keep updating UV unwrap all the time, but that would be very resource intensive task and would not be practical.